1. Field of the Invention
The present invention relates to a gamma camera apparatus for detecting gamma rays emitted from a radioisotope (RI) administered to an examinee to construct a three-dimensional image representing a distribution of the radioisotope in the examinee.
2. Description of the Related Art
Apparatus based on a combination of a radiation detector and a computer for producing images representing internal information of examinees are widely used in the medical field, for example. One typical apparatus is an X-ray CT (computerized tomography) apparatus which comprises a radiation source and a radiation detector that are disposed in confronting relation to each other and rotated around an examinee to scan the examinee, and a processor for measuring and processing absorbed values of X rays that are transmitted from the radiation source through the examinee to the radiation detector to obtain a sectional image of the examinee from the absorbed values.
The X-ray CT apparatus, however, is large in size and expensive to manufacture because of the structure that rotates the radiation source and the radiation detector around the examinee.
There have recently been developed gamma camera apparatus for detecting gamma rays emitted from a radioisotope administered to an examinee with a plurality of detectors arranged in a plane and a scintillator, and reconstructing internal information of the examinee based on the detected gamma rays.
One gamma camera apparatus that has been proposed has a encoding aperture plate having a number of apertures defined therein according to given rules and disposed in front of a scintillator, and reconstructs internal information of an examinee based on the information obtained from the encoding aperture plate. For details, reference should be made to xe2x80x9cEncoding aperture radiation-type CT using M arrayxe2x80x9d, Transactions of the Society of Instrument and Control Engineers, Vol. 28, No. 4,426/432 (1992), and xe2x80x9cReconstruction of three-dimensional distribution of 99mTc using encoding aperture CTxe2x80x9d, Instrument department of the Society of Instrument and Control Engineers, 17th sensing forum (2000).
It is a general object of the present invention to provide a gamma camera apparatus which is capable of obtaining a high-resolution image representing internal information of an examinee.
A major object of the present invention is to provide a gamma camera apparatus which is capable of obtaining three-dimensional image information of an examinee with a simple arrangement.
Another object of the present invention is to provide a gamma camera apparatus which is of a small size.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.